Gwen (Angel Coulby) strays further toward the dark side on this week's Merlin as she plots to have her husband Arthur (Bradley James) murdered. The unwitting prince still doesn't suspect that Morgana (Katie McGrath) has corrupted his darling wife - will the Queen's treachery be exposed?

Merlin (Colin Morgan) has other matters on his mind this week, with young druid boy Daegal (Alfie Stewart) turning to him for help when his sister falls seriously ill. But soon, our hero's good nature lands him in a sticky situation than even his great magic might not be able to resolve...